This invention relates to a method of treating photographic process waste liquor through concentration by evaporation and an apparatus therefor, and particularly, to a method of treating photographic process waste liquor through concentration by evaporation and an apparatus therefor, that are suited for treating waste liquor, produced along with development processing of light-sensitive photographic materials using an automatic processing machine, inside the automatic processing machine or in the vicinity thereof without need of collection by dealers.
In general, in the case of black and white light-sensitive photographic materials, the photographic processing of light-sensitive silver halide photographic materials is carried out with steps comprising developing, fixing, washing, etc. and in the case of light-sensitive color photographic materials, with steps comprising color developing, bleach-fixing (or bleaching and fixing), washing, stabilizing, etc.
Then, in the photographic processing for a large quantity of light-sensitive materials, there is employed a means in which the performance of processing solutions is constantly maintained by removing, while replenishing components consumed by the processing, components that may be concentrated during the processing by dissolving-out in the processing solution or by evaporation (for example, bromide ions in the developing solution, silver ions in the fixing solution, etc.). A replenishing solution is supplied for the purpose of the above replenishing, and a part of the processing solution is thrown away for the purpose of removing the above concentrated components in the photographic processing.
Recent years, because of environmental pollution or for economical reasons, the processing solutions and washing water as well are undergoing a change such that they are used in a system in which the quantity of the replenishment has been greatly decreased. The photographic process waste liquor is led from a processing tank of the automatic processing machine through a waste liquor pipe and thrown away in sewerages or the like after diluted with waste liquor of washing water or cooling water for the automatic processing machine.
However, because of tightened control in recent years against the environmental pollution, although it is possible to throw away washing water or cooling water in sewerages or rivers, it has been made substantially impossible to throw away the photographic processing solutions other than these [for example, developing solutions, fixing solutions, color-developing solutions, bleach-fixing solutions (or bleaching solutions or fixing solutions), stabilizing solutions, etc.]. Known methods for pollution-preventive treatment to decrease the burden to environmental pollution by photographic process waste liquor include, for example, an activated sludge method (Japanese Patent Publications No. 7952/1976, No. 12943/1976, etc.), an evaporation method (Japanese Unexamined Patent Publication No. 89437/1974, Japanese Patent Publication No. 33996/1981, etc.), an electrolytic oxidation method (Japanese Unexamined Patent Publications No. 84462/1973, No. 119457/1974 and No. 119458/1974, Japanese Patent Publication No. 43478/1978, etc.), an ion-exchange method (Japanese Patent Publications No. 37704/1976 and No. 43271/1978, Japanese Unexamined Patent Publication No. 383/1978, etc.), a reverse osmosis method (Japanese Unexamined Patent Publication No. 22463/1975, etc.), a chemical treatment method (Japanese Unexamined Patent Publications No. 64257/1974, No. 12152/1978, No. 58833/1974 and No. 63763/1978, Japanese Patent Publications No. 37395/1982 and No. 37396/1982, etc.), etc. which, however, can not be said to be sufficient. Accordingly, in general, the waste liquor is collected by waste liquor collecting dealers, and made harmless after secondary and tertiary treatments. However, because of increase in the cost for the collection, not only the fees for taking over the waste liquor is increasing year by year, but also the dealers are not willing to come to miniature photofinishing laboratories to collect the waste liquor because of its low collection efficiency, thus causing problems such that shops are full of waste liquor.
On the other hand, for the purpose of solving these problems and with an aim at making it possible to readily carry out the treatment of the photographic process waste liquor also in the miniature photofinishing laboratories, it is studied to heat the photographic process waste liquor to carry out evaporation of water to dryness or effect solidification as disclosed, for example, in Japanese Utility Model Unexamined Publication No. 71841/1985. As known in the studies by the inventors, harmful or very ill-smelled gases such as sulfite gas, hydrogen sulfide and ammonia gas may generate when the photographic process waste liquor is subjected to the evaporation treatment. These were found to be generated because ammonium thiosulfate and sulfites (ammonium salt, sodium salt or potassium salt) frequently used as the fixing solution or bleach-fixing solution of the photographic processing solutions are decomposed owing to high temperature. Moreover, at the time of the evaporation treatment, the water or the like contained in the photographic process waste liquor is vaporized in the form of vapor to increase the volume and increase the pressure in a evaporating vessel. Therefore, because of this pressure, the above harmful or ill-smelled gases may necessarily leak outside the evaporation treatment apparatus to cause great difficulties from a viewpoint of the work environment.
Now, to solve these problems, Japanese Utility Model Unexamined Publication No. 70841/1985 discloses a method in which an exhaust gas treating section comprising activated carbon or the like is provided at an exhaust pipe section of the evaporation treatment apparatus. This method, however, has a serious disadvantage that the vapor from a large quantity of water contained in the photographic process waste liquor causes sweating or moisture condensation at the exhaust gas treating section, so that a gas absorption treatment agent is covered with the water to instantaneously lose its gas absorption ability. Thus, this method has not been put into practical use.
To solve these problems, the present applicants have previously proposed a method of, and an apparatus for, treating photographic process waste liquor, in which when the evaporation treatment of photographic process waste liquor is carried out, a heat exchange means capable of condensing the vapor generated by the evaporation is provided and further the condensate water generated by condensation and also uncondensed components are treated, to discharge them to the outside.
However, there were found the following problems in the above proposal. Specifically, the vapor generated by evaporation treatment, which is condensed by the heat exchange means, may leak outside the apparatus before the vapor is led to the heat exchange means with good efficiency because of the pressure increased in the evaporating vessel at the time of the evaporation treatment. Since in such vapor the particularly ill-smelled harmful gas such as hydrogen sulfide is contained, this is not preferable from viewpoints of social environment and labor environment. Also, the uncondensed components having passed through the heat exchange means are discharged outside after they are treated by activated carbon or the like, but in this treatment, it is particularly difficult to remove sufficiently the ill-smelled gas and also the activated carbon may immediately lose its ability. Thus, there is a danger that such gas is discharged outside as it is. Still also, it has been revealed that when the waste liquor is treated by evaporation, there may occur the phenomenon of bumping as the waste liquor in the evaporating vessel is more concentrated, to cause the waste liquor to be scattered on the inner wall of the apparatus and fixed on the inner wall, resulting in troubles to impair the functions of the apparatus (for example, corrosion, drive failure, etc.). Still also, when the photographic process waste liquor is heated to treat it through concentration by evaporation, and particularly when, for example, the automatic processing machine is installed inside an office or the like, there may arise another problem that smelling gas such as ammonia gas, sulfite gas or the like are generated because of the evaporation of the photographic process waste liquor containing thiosulfate or ammonium thiosulfate. For this reason, it has been desired to treat the photographic process waste liquor without generation of ill-smelling inside the automatic processing machine or in the vicinity thereof, without recourse to the collection by dealers.